1. Field of the Disclosure
The present disclosure generally relates to circuit boards and methods for manufacturing circuit boards, and particularly to a circuit board with electrically conductive particles.
2. Description of Related Art
Typical consumer electronic products are required to have light, thin, short, and small structures in addition to powerful functions. Circuit boards are the core components of many electronic products, and normally are designed to have a multilayer structure in order to achieve high integration and a small vertical profile. The multilayer structure may be two layers, or six layers, or eight layers, or even more than ten layers.
Referring to FIG. 4, a typical multilayer circuit board 100 includes three insulating layers 101, 104 and 107, and four circuit pattern layers 105, 106, 108 and 109. The four circuit pattern layers 105, 106, 108 and 109 and three insulating layers 101, 104 and 107 are stacked and sandwiched together in alternating fashion. That is, the four circuit pattern layers 105, 106, 108 and 109 are disposed on surfaces of the three insulating layers 101, 104 and 107, with every two adjacent circuit pattern layers 105, 106, 108 and 109 being separated by a corresponding insulating layer 101, 104 or 107. A through hole 110 can be defined in the circuit board 100, and a wall of the through hole 110 can be coated with electrically conductive material to form a via. The via thereby electrically interconnects the two outermost circuit pattern layers 105 and 109.
Referring also to FIG. 5, a typical method for forming a circuit pattern on an insulating layer includes the following steps.
In step S20, an insulating layer is provided, and a copper layer and a photo-resist layer are formed on one side of the insulating layer.
In step S21, the photo-resist layer is exposed using a photo-mask, and then developed, thereby forming a photo-resist pattern, with the photo-resist pattern exposing unwanted portions of the copper layer.
In step S22, the exposed portions of the copper layer are etched away, thereby forming a circuit pattern.
During the process of manufacturing the circuit board, a lot of etching liquid or etching gas is used to etch the copper layer. These etching substances are corrosive, thus resulting in the need to provide systems for avoiding environmental pollution.
What is needed, therefore, is a method which can overcome the described limitations and an associated circuit board made by such method.